Chemical mechanical polishing (CMP) is generally known in the art. For example U.S. Pat. No. 5,177,908 issued to Tuttle in 1993 describes in finishing element for semiconductor wafers, having a face shaped to provide a constant, or nearly constant, surface contact rate to a workpiece such as a semiconductor wafer in order to effect improved planarity of the workpiece. U.S. Pat. No. 5,234,867 to Schultz et al. issued in 1993 describes an apparatus for planarizing semiconductor wafers which in a preferred form includes a rotatable platen for polishing a surface of the semiconductor wafer and a motor for rotating the platen and a non-circular pad is mounted atop the platen to engage and polish the surface of the semiconductor wafer. Process control using operative sensors for sensing the progress of polishing and process control using this progress of polishing is generally known.
An objective of polishing and/or refining of semiconductor layers is to make the semiconductor layers as nearly perfect as possible.